There were two goals of the present experiment, namely (1) to determine and compare the concentrations of basal nutrients and anti-nutrients in the grain of a modern hybrid rye and barley cultivars, and (2) to compare the effectiveness of the rye- and barley-containing diets for pig fattening. Crude protein and starch contents were greater (P < 0.01) in rye (cv. Visello) than in barley (cv. Bryl) but fibre and total lipid concentrations were lower (P < 0.01) in rye grain. Mean concentrations of alkylresorcinols and pentosans, as well as the activity of trypsin inhibitors, were all higher (P < 0.01) in rye grain. In all, 150 PIC gilts were randomly divided into two equinumerous groups; control pigs were fed a diet containing barley as the main cereal ingredient (starter phase (SP), 35% of feed content; grower phase (GP), 40% of feed content; and finisher phase (FP), 65% of feed content), while the experimental group received a diet with rye replacing a proportion of barley (10% during SP, 25% during GP and 50% during FP); the diets for both subsets of animals also contained wheat and soybean meal to obtain a proper level of nutritional value. The average weight gain of the rye-fed gilts (783 ± 183 g/day; mean ± s.d.) was greater (P < 0.05) than that of control animals (747 ± 218 g/day). This difference in weight gain was due mainly to an increase in daily feed intake (2.35 ± 0.21 and 2.15 ± 0.19 kg/day in the experimental and control groups, respectively; P < 0.01) recorded during the grower and finisher phase. Carcasses from both groups exhibited the same lean meat content; however, the percentage of carcasses in the higher classes according to the EUROP quality scale tended to be greater in the experimental group, which resulted in a higher (P < 0.05) carcass value than for barley-fed controls. The present results indicated that a modern rye cv. Visello is a safe and cost-effective feed for growing pigs, and yields significantly better outcomes than commonly used barley-containing diets in terms of carcass quality and price.